Method of producing smoke



Patented May 13, 1947 METHOD OF PRODUCING SMOKE Herbert E. Britt, Los Angeles, Calif.

N Drawing. Application February 20, 1943, Serial No. 476,619

4 Claims.

This invention relates to smoke and to a method of producing same, and more particularly pertains to smoke of the character set forth in my copending application for United States patent, Serial Number 312,228, filed January 3, 1940, which has resulted in Patent No. 2,311,635, issued February 23, 1943, and of which this application is a continuation in part.

An object of this invention is to provide a smoke which in itself is relatively harmless to human or animal life and which has no appreciable destructive effect on organic or metallic substances such as surface finishes, structural materials, and the like, when used under proper conditions, and whereby the smoke is especially applicable for use in producing the illusion of a smoke, cloud, fog or mist in photography as in the taking of motion pictures where persons, animals, and properties are subjected to the smoke, and where the smoke is apt to be respired.

Another object is to provide a smoke which is particularly adapted for use in warfare in the production of blanketing clouds which are employed in hampering the enemy, as in masking enemy observation posts and gun enplacements, and in producing screening clouds used in obscuring military positions and equipment, hiding movements of troops, vehicles and ships, and covering the construction of bridges, etc., in the face of the enemy, and which is also used in feinting operations to draw the enemys attention and create confusion.

Another object is to provide a smoke of the above character which comprises extremely fine divided solid particles suspended in air.

Another object is to provide a solid particle smoke derived from the reaction of vaporized liquids brought into contact in the atmosphere.

Another object is to produce a solid particle smoke from unidiluted liquids of relatively high boiling points whereby handling and transporting of the smoke forming materials may be effected with ease and without danger.

Another object is to provide a smoke which is inherently dry and accordingly will not wet or detrimentally afiect-objects subjected thereto.

Another object is to provide a minute particle smoke which can be readily, rapidly and economically produced in the form of a cloud, fog or mist of more than ordinary permanent and stable character whereby it will diffuse in the atmosphere very slowly and will have a low rate of settling or dissipation.

Another object is to produce a smoke having a high density or screening capacity or total obscuring power.

Another object is to provide a smoke in which the materials employed are ordinarily readily obtainable at low cost.

A further object is to provide a method of producing a smoke of the character above set forth which may be readily and economically carried out and without the employment of added or supplemental heat or without dissolving in water.

With the foregoing objects in view, together with such other objects and advantages as may subsequently appear, the invention is carried into effect as hereinafter set forth by way of example, and as defined in the annexed claims.

Generally considered the smoke constituting the subject hereof comprises a liquid amine and an organic acid which are brought together in the atmosphere with either the amine or acid, or both, in vaporous form, in such fashion that the amine and acid vapors will come into contact with each other and will react to produce a mass of line opaque particles of amine salt which will be suspended in the atmosphere and will have the appearance and effect of a white smoke, cloud, fog or mist.

Heretofore and prior to my invention it has been well known in the art that smoke or salts may be produced by uniting certain amines with certain acids such as methylamine (a gas) and hydrochloric acid. Ammonia (a gas) to which amines are closely related in chemical properties, and from which many amines are derived, has also been used to form smoke by reaction with hydrogen chloride. Such smokes are objectionable in that they may be injurious and are inconvenient and sometimes impractical to produce since the gas must be stored under pressure, or must be dissolved in a carrier liquid such as water which results in the production of a smoke of low obscuring power because of the presence of an inert dilutant and because the concentration of the active material in solution cannot 3 usually be made sufiiciently high on account of limited solubility.

In carrying out my invention an amine or a mixture of two or more amines is employed which is liquid at normal atmospheric temperatures and pressures, which possesses low viscosity, which has a relatively high boiling point, and which will react with a volatile liquid organic acid in the presence of air at ordinary atmospheric or room temperatures to produce smoke. The amines which are suitable for the purpose, some of which may be used separately and others in amine mixtures, constitute a group of amines which are characterized by two or more carbon atoms not to exceed eight in each amine molecule and having a boiling point not exceeding 179.6 C., and among which are the following:

Boiling point, degrees Ethylamine CzHsNI-Iz 18 Propylamine C3H7NH2 49 Diethylamine (CzI-I)NH 56 Butylamine C4H9NH2 63 Amylamine C5H11NH2 95 Cyclohexylamine CsHiiNHz 134 Ethylenediamine C2H4(NH2)2 116 Normal octylamine, a liquid monobasic amine having a high boiling point of 179.6 may be used.

A solid amine may be employed where it is dissolved in a highly volatile amine to produce a liquid amine mixture of requisite low viscosity and high boiling point.

The invention contemplates the use of a primary, secondary or tertiary amine of at least two and not more than eight carbon atoms, used either separately or in a mixture; the essential feature being the employment of a liquid amine having a boiling point ranging from approximately 18 C. to 179.6 C.

However, by reason of the availability of cyclohexylamine due to its ready and economical mode of manufacture at present, it is deemed by me to be most suited to the production of my smoke. Furthermore, the high boiling point of cyclohexylamine renders it easier to handle without excessive evaporation losses in handling and storage, while its greater molecular weight enhances its smoke producing qualities.

Manifestly, as above stated, certain amines may be employed separately, or in order to produce a liquid amine, of proper viscosity and reactive properties,-two or more of the amines may be used collectively. For example, an amine of high boiling point and having a viscosity which is too high for best results in atomizing to then efiectively react with the vaporized acid, may be mixed with another amine of lower boiling point and lower viscosity in such relative proportions as to produce a liquid amine mix having the desirable vaporization and reaction. For example, octylamine having a high boiling point may be mixed with ethylamine which has a low boiling point to provide a suitable amine mix. On the other hand amine which would be difficult to handle because of its low viscosity and low boiling point may be dissolved in an amine of higher viscosity and boiling point to produce a liquid of proper vaporizing, and reactive characteristics.

4 of added heat and without the necessity of dilution in Water or other medium.

The organic acid preferably employed is acetic acid, but other organic acids may be used such as formic acid, propionic acid and butyric acid. Acetic acid is desirable because of its availability and low cost, and, because of its comparatively slow corrosive action or low degree of dissociation plus the fact that it will react with an amine of the class described to produce a smoke which is relatively non-toxic and practically non-injurious, which is highly lasting in the atmosphere in which it is formed, and which has a high 0bscuring' power by reason of the amine salt particles produced by the reaction being extremely effective in reflecting light.

Any one of suitable organic acids may be employed or any two or more of such acids may be used collectively.

In forming smoke the amine and the acid are brought into intimate contact with each other in air, with either the amine or the acid, or both, in vaporous form. For example, the smoke may be formed by passing vaporized amine into or against a volume of liquid acid, or vaporized acid may be directed into or against a volume of the liquid acid, or vaporized acid may be directed into or against a volume of the liquid amine, or amine vapors and acid vapors may be brought together in atmosphere which latter mode is preferred and is highly effective. In any event the contact of the amine and acid in the air, with either the amine or the acid, or both, in the form of vapors, will result in the production of a mass of fine opaque particles consisting of amine salts which are suspended in the air in the form of a white cloud.

Any suitable spraying or vaporizing apparatus may be employed in efiecting vaporization and delivery of the atomized amine and acid, but where both the amine and acid are vaporized they are discharged from separate containers equipped with atomizing discharge nozzles which are arranged and operated in such fashion as to effect dispersion or regular distribution of the amine and acid vapors into intimate contact with each other.

Intermixture of the liquid amine and liquid. acid vapors in the production of the smoke may be effected at any temperature above the temperature at which the liquids freeze, without subjecting the liquids or the formed vapors to. any temperature treatment, and accordingly the smoke product can be produced with the liquid amine and liquid acid having a temperature like or approximating that of any surrounding atmosphere above the freezing point of the liquids.

The relative proportions of the amine and the acid are variable according to the particular amine or acid, or combination thereof asmay' be selected for use, and may vary according to atmospheric conditions such as changes in temperature, but by reason of no preliminary admixture of the amine and acids being efiected and the amine and, acids vapors being brought into. contact with each other in the air-at the time of forming the smoke, no definite proportions. of the materials need be predetermined.

Obviously from. an economical standpoint. an approximation to the chemically equivalentquantities of liquid amine and liquid acid would be most desirable; excesses of either material contributing little or nothing to the smoke. In general, the ratio of the quantity of the. amine tad-the quantity of acid used. would be the molecular weight of the amine divided by the number of active basic groups in the amine molecule to the molecular weight of the acid divided by the number of active acidic groups in the acid molecule. For example and not by way of limitation the following formula is given:

Let

a=molecular weight of amine b=number of active basic groups c=molecular weight of acid d=number of active acidic groups Then weight of base weight of acid In determining the quantity of acetic acid which would be required to go with 100 grams of ethylenediamine where such materials are to be used in the production of smoke the formula would be applied as follows:

Molecular weight ylenediami 7M2 Acetic acid 6005 Then 2 eo.05 60.05 c *39.0e gram The smoke product manufactured as herein set forth is characterized by its practically instant generation and its density; the reaction of the vaporized amine and acid being to produce a volume of white smoke composed of extremely fine particles of opaque amine salt the molecules of which when massed together form a dense cloud having high total obscuring power.

The product is characterized by its non-toxic and non-irritating character when respired under proper conditions, which renders it highly suitable for use in enveloping persons and animals, as in motion picture and military operations, in dispersing crowds and breaking up mob-s and riots, as well as in producing effects of smoke, steam, fog and mist in photographic and theatrical effects.

Most of the salts formed by the amine and acids as herein set forth have low inflammability and accordingly in most cases can be safely employed in the presence of fire.

An important feature of the invention is the fact that the liquid amine and the liquid acid to be used in the production of the smoke may be readily transported in containers without subjecing to special pressures and accordingly require no special treatment in handling and shipment preparatory to use.

While the smoke product as above set forth is complete in itself its characteristics may be altered by the addition of other ingredients. For example, an essential oil or other suitable odorizer may be added in suitable quantity to the liquid amine to impart either a pleasant or a disagreeable odor to the generated smoke.

The weight of the smoke may be increased so as to cause it to settle by the addition of a volatile liquid of low boiling point of a ketone, such as acetone, to increase the rate of evaporation of the mixed amine and acid vapors whereby cooling of the smoke will be accelerated and a greater density will be imparted thereto. Ten to fifty per cent by volume of such low boiling point liquid to a given volume of the liquid amine or acid may be used, but such proportions are not critical and may be varied as occasion requires.

A carbon chlorine compound such as carbon tetrachloride may be added to increase the weight of the smoke and also to impart fire extinguishing properties thereto. Ten to sixty per cent by volume of carbon chlorine compound to a given volume of liquid amine or acid may be used, but such proportions are not critical and may be varied as occasion requires. A paraffin halogen compound may also be used for this purpose such as ethyl or propyl chloride or ethylenedichloride.

Manifestly the smoke may be rendered toxic and lethal in character by incorporating therewith poisonous gases whereby the product could be advantageously employed in conducting gas warfare.

I claim:

1. The method of forming smoke consisting in separately vaporizing ethylenediamine and acetic acid and bringing the vaporized ethylenediamine and acetic acid into contact in the atmosphere.

2. The method of forming smoke consisting in separately vaporizing ethylenediarnine and a liquid organic acid and bringing the vaporized ethylenediamine and organic acid into contact in the atmosphere.

3. The method of forming smoke consisting in intermixing in atmosphere ethylenediamine and vaporized acetic acid in approximately the proportions of one hundred grams of the ethylenediamine and 155.99 grams of the acid.

4. The method of forming smoke consisting in bringing together in atmosphere atomized acetic acid and an atomized liquid amine selected from the group consisting of ethylamine, propylamine, diethylamine, butylamine, amylamine, ethylenediamine, and normal octylamine.

HERBERT E. BRITT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,433,732 Lewis et a1 Oct. 31, 1922 2,274,807 Rawlins et al. Mar. 3, 1942 2,315,734 Ralston et al Apr. 6, 1943 OTHER REFERENCES Clouds and SmokesGibbs, 1924, page 223.

Principles of Organic Chemistry-Norris, 2nd ed. (1922), pages 212-215.

Sharples Synthetic Organic Chemicals. Booklet of Sharples Solvent Corp. Phila. (10th ed., 1937) pages 23-24. 

